ong-rae Cho

Conformality of Pb ( Zr , Ti ) O3 Films Deposited on Trench Structures Having Submicrometer Diameter and Various Aspect Ratios

Pb(Zr,Ti)O 3 films were deposited at 540°C on trenched substrates with submicrometer diameters by pulsed-metallorganic chemical vapor deposition. The respective fluctuations of Pb/(Zr + Ti) and Zr/(Zr + Ti) molar ratios were in a range of ′19 and ′17% from each average value at the sidewalls of trenches with a diameter of 200 nm and a depth of 685 nm (aspect ratio of 3.4). The sidewall-bottom step coverage was successfully maintained above 70% up to a depth of 685 nm. The present results show the possibility of uniform Pb(Zr,Ti)O 3 film deposition on the trench substrates with high aspect ratio.

Step Coverage and Composition of Pb(Zr, Ti)O 3 Capacitors Prepared on Sub-Micron Three-Dimensional Trench Structure by Metalorganic Chemical Vapor Deposition

Pb(Zr, Ti)O 3 (PZT) films were deposited into sub-micron trench structure consisting of SiO 2 /TiAlN/Ti/SiO 2 /Si to investigate their thickness and composition conformality by pulsed-metalorganic chemical vapor deposition (MOCVD) using liquid delivery source-supply system. Bis(dipivaloylmethanato)lead [Pb(DPM) 2 ], tetrakis(1-methoxy-2-methyl-2-propoxy)zirconium [Zr(MMP) 4 ] and tetrakis(1-methoxy-2-methyl-2-propoxy)titanium [Ti(MMP) 4 ] were used as Pb, Zr and Ti source materials, respectively. In Arrhenius plot, the slopes of the straight lines for the constituents Pb, Zr and Ti in PZT film were almost the same at a lower deposition temperature ( T d ) region as well as a higher T d one. This means the composition change in the film against the T d can be suppressed by using Pb(DPM) 2 -Zr(MMP) 4 -Ti(MMP) 4 -O 2 source system. From the results of Arrhenius plot, the T d s were fixed on 450 and 540°C as lower and higher temperatures, respectively. At both T d s, the sidewall-bottom step coverage ( SC s-b ) was approximately 70 %, while the sidewall step coverage ( SC sw ) reached excellent values above 90 %. It is suggested that low SC s-b value was caused by crystallization of the PZT films at the bottom of the trench because underlayer of the film at this area was not SiO 2 but crystalline TiAlN. On the other hand, no significant composition fluctuation was observed along the depth direction of the sidewall. These results mean that the film deposited at 540°C had almost the same level in terms of thickness and composition conformality as that deposited at 450°C.

METAL-INSULATOR TRANSITIONS IN POLYCRYSTALLINE VOx THIN FILMS

ABSTRACT Metal-insulator transition properties in polycrystalline VOx thin films, which were deposited using rf magnetron sputtering with a vanadium target on Pt/Ti/SiO2/Si substrates, were studied in terms of structural and electrical characteristics. The phase change of VOx thin films by annealing was confirmed from amorphous VOx films to mixed crystalline phases containing V2O3,VO2,V6O13, and V2O5. The metal-insulator transition of VOx thin films was observed by current-voltage measurement as a function of top-electrode area and the temperature. It was demonstrated that the VOx thin films can be applied to memory devices employing the transition from a high-resistance (off) insulating state to a low-resistance (on) metallic state.

Effects of Pre-Deposition Gas Treatments for Pb(Zr,Ti)O3 Films on Ir Electrode Grown by MOCVD

ABSTRACT In order to decrease the effect of an interface dead layer, we improved PZT thin film properties that have highly preferential (111) orientation [R(111) = 88%] and good electrical results [71 μC/cm2] with optimized N2 and O2 gas treatment prior to PTO and PZT deposition. From XPS result shows that creating a homogeneously crystal structure is the main key of high performance ferroelectric thin film technology. In addition, PZT capacitor device with N2 and O2 pre-deposition gas treatment have 90% non-volatile charge.